Conventional disk drives typically include a base plate and a cover that is detachably connected to the base plate to define an enclosure for various disk drive components. One or more data storage disks are generally mounted on a spindle which is rotatably interconnected with the base plate and/or cover so as to allow the data storage disk(s) to rotate relative to both the base plate and cover via a spindle motor. An actuator arm assembly (e.g., a single actuator arm, a plurality of actuator arms, an E-block with a plurality of actuator arm tips), is interconnected with the base plate and/or cover by an appropriate bearing or bearing assembly so as to enable the actuator arm assembly to pivot relative to both the base plate and cover in a controlled manner.
A suspension or load beam may be provided for each data storage surface of each data storage disk. Typically, each disk has two of such surfaces. All suspensions are appropriately attached to and extend away from the actuator arm assembly in the general direction of the data storage disk(s) during normal operations. A slider is mounted on the free end of each suspension. A transducer, such as a read/write head, is mounted (e.g., embedded) on each slider for purposes of exchanging signals with the corresponding data storage surface of the corresponding data storage disk. In this regard, each data storage surface of each data storage disk has a plurality of concentrically disposed tracks that are available for data storage. Typically, these tracks are circular and are concentrically disposed on a data storage disk of a disk drive.
For high track density drives, the position of the slider, and thereby each transducer, is often controlled by a “dual-stage actuation system”. In such a system, a first stage including a voice coil motor or the like is utilized to provide a course positioning by pivoting the actuator arm assembly and each slider interconnected therewith to dispose the transducer(s) at a desired radial position relative to the corresponding data storage disk. In a second stage, a microactuator is utilized to further position the transducer(s) at a radial position over a desired track. In this regard, such microactuators typically operate to move the transducer radially over the disc surface for track seek operations and hold the transducer directly over a track on the disc surface for track following operations. One type of microactuator includes a pair of piezoelectric (“PZT”) elements that expand and contract in response to an applied voltage to distort the slider to effect fine positioning of the transducer and slider relative to a desired track.
Disk drives also often include different systems to protect against damage to the data storage disk(s) and/or transducer(s) in the event that the disk drive is subject to a non-operational shock event or force (“shock event”). For instance, disk drives may include a sensor system that detects shock events and prevents read/write operations until the event has subsided. In another instance, disk drives may include an active damping system, which actively dampens vibrational energy from a shock event, to reduce damage. In either case, it is known to use piezoelectric materials in these systems. For example, in the case of shock sensors, it is known to use a pair of piezoelectric elements mounted on a disk drive housing to detect shock events and prevent read/write operations during such an event to prevent damage to the disk(s) and/or transducer(s).
Currently, several methods exist for testing microactuators and sensors that include piezoelectric materials. These methods generally include, measuring capacitance, performing visual checks, and/or measurement of a mechanical resonance using a Laser Doppler Vibrometer (“LDV”) to generate a mechanical bode plot. Among these methods, the most reliable is the use of an LDV to measure mechanical resonance. The output of the LDV test (a bode plot representing the mechanical resonance characteristics) may then be compared to known resonance characteristics of an operational microactuator and/or to determine if the microactuator and/or sensor is functioning properly. In this regard, if the subject microactuator and/or sensor is damaged, such resonance characteristics will vary indicating that the subject microactuator and/or sensor should be further tested, usually via close visual inspection, for damage. LDV involves projecting a laser beam onto one of the PZT elements to sense and measure motion of the element that may be characterized in a graphical output, usually including a plot of the log of the frequency versus the measured vibration in decibels.
Unfortunately, however, LDV mechanical resonance measurement is inefficient in that it requires significant setup and positioning to align the laser beam on the measurement target (one of the PZT elements). Further, in some cases, such as within an environmental chamber or when a subject disk drive is completely sealed, LDV testing is not even possible without removing and/or disassembling the subject drive to expose the measurement target to the laser beam. In this regard, the average testing time for a single microactuator using the LDV method is on the order of about half an hour to an hour. This in turn oftentimes makes microactuator and/or sensor testing using LDV economically infeasible.